A commonly held misconception is that the energy in infrared light is too low to drive photosynthesis for practical food production and biomass production. This misconception stems from the well-known fact that the higher the frequency of light, the greater the energy of the light photon, which is expressed in the relationship E=hf (where E=energy of photon, h=Planck's constant, f=frequency of photon).
In this commonly held misconception, the wavelength (and thus energy) of the photons of incident light determines the amount of energy stored during photosynthesis (such as the amount of energy stored in bonds of the “energy carrier molecules”, such as during cyclic photophosphorylation of ADP to ATP by PS-I or Z-Scheme involving PS-I and PS-II resulting in both ATP and NADPH).
This misconception is incorrect. For instance, a photon of blue light at 488 nm has about 30% more energy than a photon of red light at 633 nm. But, in fact, both photons may impart the same amount of energy when used by bacteriorhodopsins (bR), reaction centers (RC), photosystems-I-II (PS-I and -II) or any photosynthetic membrane protein-chromophore complexes.
This is because even though the absorption peaks of these photosynthetic molecular complexes vary, the absorption curves may be spread out over hundreds of nanometers and only the external action spectra efficiencies may be affected by the distribution of wavelengths of the source light while the internal quantum yields may depend on process pathways. (The number of O2 molecules evolved per incident photon is a hotly debated issue among scientists, with accepted values between ⅛ and 1/12) The photosynthetic process itself may be largely agnostic to the color of incident photons, depending instead on the total excess number of photons absorbed per unit area per unit time.
For instance, it is commonly held that green plants only absorb the red and blue parts of the solar spectrum rejecting the green due to the absorption spectrum peaks of ChlA and ChlB pigments. This is an explanation often given as to why plants appear mostly green. What is more, conventional schemes for efficient growth that are based on this understanding rely on using red and blue LEDs only.
In fact, photosynthesis may proceed just as well with any color of light in circumstances where the total number of co-incident photons absorbed per unit area per unit time does not fall below a photosynthetic threshold of 8-12 per photons absorbed in the time window corresponding to the relaxation characteristic time for PS-I and PS-II.
Of course, the organism may be sensitive to large fluxes of ultraviolet light (which is absorbed by both DNA and proteins causing damage) or to large fluxes of infrared light (which when absorbed by the water in the cytoplasm may elevate the temperature, causing damage by protein denaturation and errors in nucleic acid polymerization reactions).
It is worth noting that green photons alone may be sufficient to drive photosynthesis.
The abundant pigment-protein membrane complex photosystem-I (PS-I) is at the heart of the Earth's energy cycle. It is the central molecule in the “Z-scheme” of photosynthesis, converting sunlight into the chemical energy of life.
PS-I precisely orchestrates 96 chlorophyll molecules with electron donors and acceptors achieving efficient coherent energy transfer and near-unity charge separation quantum yield at ambient temperatures. This is a feat unmatched by any man-made photoelectronic device and has led to PS-I being studied as a candidate for many nanobioelectronic applications
The energy for photosynthesis depends on photon flux gradients (number of photons per time per area going one way versus the other way). The absorption peaks of reaction centers and PS-I and PS-II are not tuned to harvest max E=hf (or they'd be in the green); instead they're tuned to harvest max photon flux gradients.